How Important Are Consumer Species to Ecosystem Functioning?

Summary

Species-level and ecosystem-level perspectives can often be combined to better understand nature. To date relatively few studies have explicitly combined these two perspectives; however, the insights these studies offer have been impressive. Considering species as embedded in ecosystems and as potentially having feedback effects that can alter ecosystem function is a powerful way of conceptualizing and analyzing ecological systems. Ecosystem-level phenomena constrain the populations and behavior of consumers, and the effects of consumers seem often to be mediated by changes in ecosystem functions such as productivity, nutrient cycling, and nutrient flows across ecosystem boundaries. These changes often are caused by nontrophic as well as trophic activities, and they may involve changes in behavior of plants. Just how commonly particular herbivore species will prove to control ecosystem functioning remains to be tested in many systems, using techniques with adequate power to discriminate ecologically meaningful effects.